- This creature is the true form of Forbidden.
- This creature has the second highest power of any creature in the game, at 99999. The highest is Dormageddon X, Forbidden Armageddon. They only have Triple Breaker instead of World Breaker, however.
- This creature is the card with the second highest numbered and second highest printed cost in the game, at a cost of 99. The first is Dormageddon X, at a cost of 999.
- According to the Duel Masters Battle Arena Final Edition comic, this card was developed in a duration of 6 months and is the first card to be developed in such a long time.
- This creature's DMR-19 Forbidden Dokindam X artwork bears resemblance to the murals of the Diamonds from Steven Universe. Additionally, the Diamonds were the strongest characters in that franchise.
- This creature's name comes from the Japanese term "Doki" which means heartbeat, which is also referenced to in its Forbidden Impulse side. In the anime, faint heartbeats are heard when Basara unseals it.
- It might be also an angaram on DM (Duel Masters) and Kindan (Forbidden).
- In the background story, this creature was a long sealed existence who was used and unsealed by Gyuujinmaru, Legendary Identity to rule the world. At the end of the Revolution block, it suddenly goes into a rampage and kills Gyuujinmaru then proceeds to kill everybody regardless of Revolutionary, Invader or The Answer as well as creating massive amounts of Initials which plunged the continent into darkness. As unlike most major antagonists, it was not dealt with at the end of the block and its influence still stands strong at the next block, and it also defeated all fractions in Revolution all by itself directly (Unlike Codename Sherlock who killed the main protagonists by a surprise attack), it can be considered among one of the strongest antagonists of Duel Masters.
- It was later defeated by Dogiragon Buster, Blue Leader and Puchohenza, Mia Moja with the help of Wachagona, Muen Zangu, but his power still remains and hands his role to VV-8, Forbidden Machine and Blackout, ZERO Invasion. As the mother Forbidden in his planet, FORBIDDEN ~Star of Forbidden~ does not die, his power will still remain and will continue to wreak havoc into the creature world.
- However, he is revealed to be just about as strong as Lionel, Zenith of "Ore", which was defeated easily by the Dragon Saga ruling Dragons like Dorago the Great, Dragon World. This indicates that after the defeat of All Over The World, Supreme True Dragon Soul, the power of the Dragons in the planet are severely weakened to the point that would be simple threats for the Dragons before became extreme ordeals.
- In DMR-21 Team Hamukatsu and Dogiragon Buster, it was reprinted. This time, it had gold foil on the Forbidden ~The Sealed X~ side and the Dokindam X side was a 3D plastic film with Dokindam X throwing its Seals. Therefore, the card is a 3D plastic film with a thin sheet of paper on it as its Sealed X side. Due to this, the card is extremely thin and soft and it is advised to use a sideloader to contain it if the player wants to play the card.
- This also makes it the first card to be in a regular booster pack that is not made of cardboard paper. As such, it is not advisable to feel the packs for rare cards as this card may get damaged.
- In the anime, it was considered as one of the most dangerous cards in the World of Duel Masters.
- Lucifer considered the card to be too dangerous to be under the organization and Basara's hands that he monitored the activity within Duel Masters Land and took immediate action.
- Shobu Kirifuda even considered the card's power as a threat, possibly due to its connection to his nemesis Zakira and had witnessed Katta's duel against Basara, who was under the influence of the card. Though his research about the warring races, he took action to train Katta Kirifuda and prepares Bolshack Dogiragon as a countermeasure.
- Its threat is being proved by its ability to corrupt its owner Basara, giving him X marks on his hand, making his hair grow long, making him have grayer skin and having Forbidden text appear on it, as well as changing his personality into a more destructive one.
- In the manga, it even causes him to grow claws from his fingers and turns his hand into those similar to Forbidden ~The Sealed X~. This process is revealed to be happening in the trailer for Duel Masters Versus Revolution Final as well, meaning that Basara might end up fully possessed in that season.
- In Duema TV, this card and the duema hero of Tokyo has possessed Duema Star Taka which caused him to destroy all duema heroes in Japan. The possession is still happening currently, but it has been stopped by Duema Boy Daiki with the combo of Miracle Miradante, Amaterasu Seraphina, Light Weapon and Glorious Tactics.
- This creature's alternate loss effect is represented in the anime that it would kill its owner along with it should it go anywhere outside the battle zone.
- This card is the first card in Duel Masters to make a One-turn Kill Possible in combination with All Delete and Cosmic Darts.
- Dokindam X in DMR-19, Redzone X, Forbidden Lightning Sonic and Dormageddon X, Forbidden Armageddon share the same posture in their card artwork.
- This card's secret version's Forbidden Characters text can be translated to the following:
| KNDN LEGEND DKDM X |
kndn legend dkdm x
|Fire / KNDN Creature / 99 / 99999|
| ■ Triple breaker |
■ When this card is flipped to this creature side, your opponent puts a seal on each of his creatures.
■ Whenever a spell that costs 4 or less would cause your opponent to choose a creature, he can't choose this one.
■ If this card is anywhere other than the battle zone, you lose the game.
|Artist: [[MITSUAKI MATSUMOTO|mtsk mtmt]]|
|Dokindam X, The Legendary Forbidden|
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